South Tarawa is home to most of the Government, commercial and education facilities in Kiribati including the Port and the High Court at Betio, the State House, Government Ministries and foreign High Commissions in Bairiki, a University of the South Pacific campus in Teaorereke, the House of Assembly (Kiribati) in Ambo, the Kiribati Teacher College and Government High School in Bikenibeu, and the central hospital in Nawerewere.

 The Roman Catholic diocese is based in Teaorereke, the Kiribati Protestant Church (Congregational) in Antebuka, and The Church of Jesus Christ of Latter-day Saints in Eita.

At the local government level, South Tarawa has two administrative subdivisions:

Betio Town Council (or BTC), on Betio;

Teinainano Urban Council (or TUC), from Bairiki to Tanaea (The meaning of Teinainano is "down of the mast", alluding to the sail-shape of the atoll).

Buota, which is part of North Tarawa and administered by the Eutan Tarawa Council (or ETC), is linked by road to South Tarawa and is experiencing many similar issues of rapid population growth, urbanisation and environmental degradation.

South Tarawa is a string of islets between the Tarawa Lagoon to the north, with a maximum depth of 25 metres (82 ft), and the Pacific ocean to the south, with a depth of up to 4,000 metres (13,000 ft).The island has been built from sediments from the lagoon.

 The process of soil accumulation is driven by the dominant easterly trade winds, and can be reversed during extended periods of westerly winds during El Niño–Southern Oscillations.[6] All of these islets are now joined by causeways, forming one long islet on the reef along the southern side of the Tarawa Lagoon. Most of South Tarawa is less than 3 meters above sea level with an average width of only 450 meters.

At the time of the 1978 Census, South Tarawa had a population of 17,921 with most residents living in the main population centres of Betio, Bairiki and Bikenibeu,. Since Kiribati became independent in 1979, the population of South Tarawa has almost tripled, and now stands at 50,182 people. All of South Tarawa is now urbanised, and is effectively one continuous settlement from the Northeastern end of the island, Tanaea, to its Southwestern end at Betio. Buota in North Tarawa is also connected to the South Tarawa main road and is also growing rapidly.